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IX. A Description of the solvent Glands and Gizzards of
the Ardea Argula, the Casuarius Emu, and the longlegged Casowary, from Nero South Wales. By Sir Everard Home, Bart. F.R.S.
The principal difference in the structure of these organs, as described in this paper, is in their magnitude, in the number of cells of which each gland is composed, and in the situation which they occupy, in the cardiac cavity, circumstances which may probably have some relation to the quality of their food, and the ease with which it may be digested. The glands of the Casuarius Emu, which is a native of the fertile island of Java, are of small size; and it is an instance of design deserving of particular notice, that the gizzard in this bird is so placed, that the food may pass along the canal without being subjected to its grinding operation, and it appears, therefore, to be called only into occasional employment; while the Struthio Camelus, which inhabits the deserts of Africa, has glands of a more complex structure, and the gizzard is so situated, that the whole of the fuod must be submitted to its action.
There is also a most remarkable difference in the length of the intestinal tube in each, which Sir Everard Home conjectures to be connected with their circumstances as to food, the former being only six feet in length, while in the latter they are seventytwo feet. These are the two extremes, and the whole seem to form a series in which the structure of the digestive organs becomes the more fitted to economize the food, when the country, which each species inhabits, becomes less fertile, and the supply of food consequently more precarious, because less abundant. X. Additional Remarks on the state in which Alcohol exists
in fermented Liquors. By William Thomas Brande, Esq. F.RS.
In a former communication, inserted in the Transactions for the year 1811, Mr. Brande adduced pretty strong evidence in support of the opinion, that the alcohol obtained from wine, by distillation, was merely separated by that process ; but still the proof could not be considered as demonstrative, until it could be shewn that the alcohol might be procured in a separate state by means purely chemical, such as were known to be capable of effecting the separation of alcohol from water. This Mr. Brande bas at length accomplished, and the details are given in the paper now before us." In order to effect the separation of alcohol from wines, it is requisite that the colouring and extractive matter be previously separated, which Mr. Brande has found may be readily effected by the acetate, or subacetate of lead, or the subnitrate of tin. The addition of either of these substances to wine, occasions a dense precipitate to be thrower down, but the subacetate of lead is the most powerful in its action, and occasions the most immediate and perfect separation of these matters, as well as of the acid which wine usually contains. After this precipitation of the colouring and extractive matter, a colourless liquid is obtained, from which the alcohol is speedily separated by the addition of dry subcarbonate of potash. The proportion of the subacetate of lead, enıployed by Mr. B. was about oneeighth of a concentrated solution, but a little excess is of no importance, since it does not interfere with the result. The proportion of alcohol obtained from wine by this means, corresponds very nearly to the proportion afforded by distillation, except when the proportion contained in any wine is below 12 per cent.
Mr B. considers the action of the subcarbonate of potash not an accurate test, for this agent produced no separation in a dilute solution of alcohol in water containing 4 per cent; and in a solution, containing 8 per cent, it effected the separation of only seven parts ; but in stronger solutions, containing sixteen or twenty parts, it always separated the whole within 0-5 per cent. The proportion of alcohol obtained, therefore, from the different kinds of wine by this method, corresponded very nearly to that obtained by distillation, as stated in the table given with Mr. Brande's former communication. From an examination of a number of specimens of what were considered good port wines, Mr. Brande has deterinined their average strength to be about 22 per cent. of alcohol, by measure.
There can be no doubt, now that these facts are ascertained, that the colouring and extraction matter contained in wines, have a very important influence in modifying the effect of the large proportion of alcohol which they contain ; for the different effects produced by the potation of wine, and of spirit and water of the same degree of strength, is a matter of general experience. To what change the improvement of wine, by age, is to be attributed, we have yet to learn.
XI. On a new Variety in the Breeds of Sheep By Colonel
David Humphreys, F.R.S. In a Letter to the Right Hon. Sir Joseph Banks, Bart. K.B. P.R.S.
Colonel Humphreys bas here presented us with a curious history of a new variety of sheep, which originated in the flock of an American farmer, residing in the state of Massachusetts. It appeared, in the first instance, in a single male individual, the peculiarity, or, rather, deformity of whose structure, was afterwards propagated in the flock, in the expectation that it would be advantageous to the farmer, from its being less capable of making its way over the fences, in a country where the fences are, in general, less secure than with us.
This breed is distinguistred principally by the shortness of the fore-legs, which are always bent like an elbow, and the feet are turned inwards in walking, so that their gait is awkward, and they can neither run nor leap so well as other sheep. Their general organic structure appears, also, to be more infirm, and they do not fatten so well as the common breeds. into an inclosure with other sheep, they are observed to separate themselves into a distinct flock.
The most remarkable circumstance in this account, is, the facility with which this peculiarity of form was propagated, so as to establish a distinct and permanent variety; and the fact is the more important, as it furnishes us with a satisfactory theory of the origin of the varieties which exist among other genera of animals.
XII. Experiments to ascertain the coagulating Power of the
Secretion of the gastric Glands, By Sir Everard Home, Bart. F.R.S. Communicated by the Society for promoting the Knowledge of Animal Chemistry.
The property of coagulating animal fluids, which is possessed by the internal membrane of the stomach of animals, is well known; and the object proposed by these experiments, was, to determine whether this property belonged to the whole of the secretions poured out by the internal membrane, or was peculiar to that formed by the gastric glands, and was communicated by that medium to the other secretions found in the cavity of the stomach. With this view some experiments were first made with the internal membrane of the stomach of several quadrupeds, birds, and fishes. No part of the membrane of the hog's stomach, possessed the coagulating power, except that near the pylorus where the glands are situated. Both the crop and gizzard of birds were found to produce coagulation ; but the gizzard was the most speedy in its effect. The stomachs of the shark, salmon, and thornback, were found to possess the same property, but in different degrees.
The gastric glands were next dissected from the stomach of turkey recently killed ; care being taken to remove them without making any opening through the inner membrane. A comparative experiment was then instituted with equal weights of these glands, and of the internal membrane of the turkey's stomach, and of that of the calf, in its recent and dried state. They all coagulated milk, but the membrane of the stomach of the turkey, was the most slow and feeble in its action.
From these results Sir Everard thinks himself entitled to conclude, that it is the fluid secreted by the gastric glands that alone possesses this power, which it communicates to all the rest. This inference does not appear quite so well established to us as it does to its Author ; nor can we assent to the truth of the concluding remark, that Coagulation appears to be the • first change the food undergoes in the process of digestion ;' because this is a change which seems to belong only to albuminous fluids; and the first action of the digestive process on alimentary matter, already firm and solid, must undoubtedly be directly solvent.
XIV. An Appendix to Mr. Ware's Paper on Vision. By
Sir Charles Blagden, F.R.S. In confirmation of the views of Mr. Ware, that short-sightedness occurs most frequently in the higher classes, particularly among the students at the Universities, Sir Charles Blagden here relates the progress of this affection as it occurred in his own person. At that early period of life when education usually commences, bis vision was extremely perfect; but he became short-sighted as he grew up, though it was in the commencement so trifling as to be corrected by common watch glass. It afterwards increased so much as to require the use of a concave glass, of low number, which was changed for others, successively, of higher numbers, as the affection became more troublesome. He attributes it entirely to a habit of study, and fondness for reading, acquired in early life, and the influence of which, on his vision, was not corrected by the occasional intervention of any oceupation or amusement which required the eyes to be directed to distant objects. Sir Charles observes, that
• Children born with eyes which are capable of adjusting themselves to the most distant objects, gradually lose that power soon after they begin to read and write ; those who are most addicted to study become near-sighted more rapidly; and if no means are used to coun. teract the babit, their eyes at length lose, irrecoverably, the faculty of being brought to the adjustment for parallel rays.'
He relates an experiment which he made many years ago, to determine how far the similarity of the images, seen by each eye, contributed to make them impress the eye as one.
The objects selected were the alternate cavities and ridges of a fluted marble chimney-piece; and when the optic axes were so adjusted, that the first ridge and concavity of the fluting, as seen by one eye, should fall in with the second ridge and concavity, as seen by the other eye, the fluting appeared perfectly distinct
and single, but it appeared to be about double the distance that it really was from the eye, and, consequently, to be magnified in proportion. XV. 4 Method of drawing extremely fine Wires. By Wi
liam Hyde Wollaston, M. D. Sec. R. S. The contrivance recommended by Dr. Wollaston for this purpose, is extremely simple, and of very easy application in practice. A wire of gold or platina, is to be introduced into the centre of a rod of fine silver, which is then drawn into fine wire by the usual means. As silyer wire used for lace and embroidery, is frequently as fine as the zoo of an inch in diameter, if the gold wire introduced into the centre of the rod has to the diameter of the silver, then, when it is drawn into wire of sto of an inch, the diameter of the gold will be zoto of an inch, and of such wire 550 feet will weigh only one grain. By these means, however, Dr. W. reduced platina to the extreme tenuity of yoooo of an inch in diameter, but the tenacity seemed to be impaired when the fineness exceeded pooo of an inch, and wire of this diameter supported of a grain before it broke. The silver coating is easily removed from these wires by nitric acid ; but, as when they exceed in fineness the moon, or yooo of an inch, they are managed with difficulty, from being easily disturbed by slight currents of air, and from being nearly invisible, and not at all perceptible to the touch ; Dr. W. recommends that the silver coating should not be removed from the extremities, and by this means they are kept stretched, and are easily applied to the purposes for which they are wanted. XVI. Description of a single lens Micrometer. By Wil
liam Hyde Wollaston, M. D. Sec. R. S. This instrument is admirably adapted for the purpose of measuring the diameter of the extremely fine wires, which are occasionally employed in the construction of philosophical in-. struments. Its external form is that of a common telescope, onsisting of three tubes. The scale by which the object is measured, occupies the place of the object glass, and consists of a series of small wires about to of an inch in diameter, equidistant from each other, and formed into divisions by a regular variation in the length of the wires with a view to facilitate the computations of the observer. This then forms a scale di equal parts. The lens is placed at the smaller end of the instrument, and having a focal length of only fī of an inch, it admits a small perforation to be made in the brass mounting at the distance of about ış of an inch from its centre, through